Typical drywall (sometimes referred to as sheetrock) installation requires three basic steps: installing (or hanging), taping and finishing. Installing is the process of fastening dimensionally sized boards of gypsum drywall to framing members of a wall or ceiling. Taping is the process of bridging and filling gaps between drywall boards. Finishing is the end process of covering the tape and fully filling and smoothing the gaps between the drywall boards, as well as filling and smoothing over screw or nail holes and other imperfections in the drywall surface. The goal in finishing is a substantially flat surface between boards such that, when painted, joints between two drywall boards are substantially undetectable. This process usually requires at least two applications of joint compound, (sometimes referred to as mud) on top of tape, with a broad flexible spreading tool. The mud is spread over seams, holes and imperfections. After each layer of mud is allowed to dry completely, the area must be sanded to reveal voids, remove tool marks, ridges of mud and other imperfections.
Construction workers who sand drywall at the finishing stage of installation are exposed to high concentrations of dusts containing talc, calcite, mica, gypsum and in some cases silica. Some of these materials have been associated with varying degrees of acute and chronic eye, nose, throat and respiratory tract irritations. When silica is present, workers also face the risk of silicosis and lung cancer. Any reduction in airborne dust is beneficial to every person involved in the construction process. Eliminating dust at the drywall finishing stage means fewer workers and residents exposed to hazardous dust.
Workers who are comfortable are more productive, and a cleaner work environment results in a superior drywall finish. Reducing or eliminating dust is particularly important in buildings such as hospitals, banks and office complexes that often require remodeling as fine airborne dusts can wreak havoc with sensitive and costly machines. Fine dust particles are spread far from the source through air exchange systems in buildings, necessarily exposing such machines to potential damage.
Conventional abrasive sanding deposits large amounts of dust on walls and ceilings, and also abrades the drywall paper, leaving visible fuzz. Painters are obliged to meticulously back-roll a primer coat in order to “lay down” this dust and fuzz. Back-rolling is both time-consuming and laborious, meaning longer exposure to paint fumes and more expense for builders. Even with back-rolling, the different textures of smooth drywall, fuzz and dust under the paint can show through. Also, conventional sanding leaves scratch marks in the finished surface.
A National Institute of Occupational Safety and Health (NIOSH) Health Hazard Evaluation found that drywall finishers, when sanding, were exposed to as much as ten times the permissible limit of total dust set by the Occupational Safety and Health Administration (OSHA). The limit for respirable dust (very small particles that can migrate deep into a person's lungs) was also exceeded.
Drywall finishers are advised to wear safety glasses, but safety glasses are impractical because the lenses become obscured with dust and fogged from the drywall finisher's breath escaping from the face mask.
Existing systems for reducing dust require the drywall finisher to be hooked up to an industrial vacuum cleaner. Such systems are expensive, cumbersome and noisy. Drywall finishers must drag the vacuum apparatus around, ensuring the hose does not kink or tangle, and ensuring that the apparatus does not damage finished corners. Vacuum systems also require electrical power, which may not be conveniently available during construction. Vacuum hoses and electrical cords pose a serious hazard to drywall finishers on stilts, and may be unusable on scaffolding. Drywall finishers must also endure the inevitable noise produced by such vacuum systems. Furthermore, vacuum based systems still emit dust through the exhaust, and vacuum exhaust tends to blow settled dust back into the air.
In another NIOSH study, five drywall compound manufacturers' material safety data sheets warned workers to avoid generating dust and to use respiratory protection when sanding. “Respiratory protection” generally means a flimsy mask that does not always fit properly, and is hot and uncomfortable. The report also advised wet sanding whenever possible. Wet sanding involves using a special sanding sponge. The sanding sponge requires frequent rinsing and wringing out, making the process more labor-intensive than dry sanding. A bucket of water must be carried with the worker at all times, and the water must be changed once it becomes too murky. Wet sanding is generally avoided in actual work practice because it is more labor intensive than dry sanding.
Consequently, it would be advantageous if an apparatus existed that is suitable for dust free finishing of drywall.